#!/bin/bash

# Script for pulling a github pull request
# along with generating a merge commit message.
# Example usage for pull request #6007 and /next branch:
# git fetch
# git checkout origin/next
# ./scripts/pull_github_pr.sh 6007

set -e

shopt -s extglob

trap 'echo "error $? in $0 line $LINENO"' ERR

gh_hosts=~/.config/gh/hosts.yml
jenkins_url="https://jenkins.scylladb.com"
ORANGE='\033[0;33m'
NC='\033[0m'

if [[ ( -z "$GITHUB_LOGIN" || -z "$GITHUB_TOKEN" ) && -f "$gh_hosts" ]]; then
	GITHUB_LOGIN=$(awk '/user:/ { print $2 }' "$gh_hosts")
	GITHUB_TOKEN=$(awk '/oauth_token:/ { print $2 }' "$gh_hosts")
fi

if [[ -z "$JENKINS_USERNAME" || -z "$JENKINS_API_TOKEN" ]]; then
  echo "
    JENKINS_USERNAME or JENKINS_API_TOKEN is missing from env.
    To create a TOKEN, browse to https://jenkins.scylladb.com, then click on your username (upper right corner) and configure. Click on Add new token and set the JENKINS_USERNAME and JENKINS_API_TOKEN environment variables accordingly.
  "
  exit 1
fi

for required in jq curl; do
	if ! type $required >& /dev/null; then
		echo Please install $required first
		exit 1
	fi
done

FORCE=0
ALLOW_SUBMODULE=0

function print_usage {
cat << EOF
Usage: ${0} [options] PR_NUMBER

Script for pulling and merging a pull request.

Fetches the PR locally and merges it into current branch. The branch must be named next*.

PR with a single commit in it is cherry-picked and thus the merge commit is not created and
the PR description is lost.

By default, doesn't merge PR that contains a submodule update, use --allow-submodule option
to proceed.

Options:

-h
    Print this help message and exit.

--force
    Do not check current branch to be next*
    Do not check jenkins job status

--allow-submodule
    Allow a PR to update a submudule
EOF
}

while [[ $# -gt 0 ]]
do
    case $1 in
        "--force"|"-f")
            FORCE=1
            shift 1
            ;;
        --allow-submodule)
            ALLOW_SUBMODULE=1
            shift
            ;;
        +([0-9]))
            PR_NUM=$1
            shift 1
            ;;
        "-h")
            print_usage
            exit 0
            ;;
        *)
            echo "error: unrecognized option: $1, see $0 -h for usage" >&2
            exit 1
            ;;
    esac
done

if [ -z "$PR_NUM" ]; then
	echo Please provide a github pull request number
	exit 1
fi

curl() {
    local opts=()
    if [[ -n "$GITHUB_LOGIN" && -n "$GITHUB_TOKEN" ]]; then
        opts+=(--user "${GITHUB_LOGIN}:${GITHUB_TOKEN}")
    fi
    command curl "${opts[@]}" "$@"
}

set_jenkins_job() {
  branch=$(git rev-parse --abbrev-ref HEAD)
  version="${branch#next-}"
  product=$(awk -F'=' '/^PRODUCT/ {print $2}' <SCYLLA-VERSION-GEN)
  case "$product" in
    scylla) folder_prefix="scylla";;
    scylla-enterprise) folder_prefix="enterprise";;
    *) echo "None supported product, valid options scylla|scylla-enterprise"
      exit 1
  esac

  case "$branch" in
    next) jenkins_job="scylla-master/job/next";;
    next-enterprise) jenkins_job="scylla-enterprise/job/next";;
    next*) jenkins_job="$folder_prefix-$version/job/next";;
    *) echo "You are running the script from branch: $branch. Valid branches: next|next-enterprise|next-*"
      exit 1
  esac
}

check_jenkins_job_status() {
  set_jenkins_job

  lastCompletedJobName="$jenkins_url/job/$jenkins_job/lastCompletedBuild"
  getBuildResult=$(curl -s --user $JENKINS_USERNAME:$JENKINS_API_TOKEN $lastCompletedJobName/api/json?tree=result)
  if [[ $getBuildResult =~ (Access Denied|401 Unauthorized) ]]; then
      echo -e "${ORANGE}WARNING:${NC} Access Denied to $lastCompletedJobName. \nPlease check your JENKINS_USERNAME and JENKINS_API_TOKEN setting"
      exit 1
  fi

  lastCompleted=$(echo "$getBuildResult" | jq -r '.result')

  if [[ "$lastCompleted" == "SUCCESS" ]]; then
      echo "$lastCompletedJobName is stable"
  else
    echo -e "${ORANGE}WARNING:${NC} $lastCompletedJobName is not stable"
  fi
}

if [[ $FORCE -eq 0 ]]; then
  check_jenkins_job_status
fi

NL=$'\n'

# convert full repo URL to its project/repo part, in case of failure default to origin/master:
REMOTE_SLASH_BRANCH="$(git rev-parse --abbrev-ref --symbolic-full-name  @{upstream} \
     || git rev-parse --abbrev-ref --symbolic-full-name master@{upstream} \
     || echo 'origin/master')"
REMOTE="${REMOTE_SLASH_BRANCH%/*}"
REMOTE_URL="$(git config --get "remote.$REMOTE.url")"
PROJECT=`sed 's/git@github.com://;s#https://github.com/##;s/\.git$//;' <<<"${REMOTE_URL}"`
PR_PREFIX=https://api.github.com/repos/$PROJECT/pulls

echo "Fetching info on PR #$PR_NUM... "
PR_DATA=$(curl -s $PR_PREFIX/$PR_NUM)
MESSAGE=$(jq -r .message <<< $PR_DATA)
if [ "$MESSAGE" != null ]
then
    # Error message, probably "Not Found".
    echo "$MESSAGE"
    exit 1
fi
PR_TITLE=$(jq -r .title <<< $PR_DATA)
echo "    $PR_TITLE"
PR_DESCR=$(jq -r .body <<< $PR_DATA)
PR_LOGIN=$(jq -r .user.login <<< $PR_DATA)
echo -n "Fetching full name of author $PR_LOGIN... "
USER_NAME=$(curl -s "https://api.github.com/users/$PR_LOGIN" | jq -r .name)
echo "$USER_NAME"

BASE_BRANCH=$(jq -r .base.ref <<< $PR_DATA)
CURRENT_BRANCH=$(git rev-parse --abbrev-ref HEAD)
TARGET_BASE="unknown"
if [[ ${BASE_BRANCH} == master ]]; then
    TARGET_BASE="next"
elif [[ ${BASE_BRANCH}  == branch-* ]]; then
    TARGET_BASE=${BASE_BRANCH//branch/next}
fi
if [[ "${CURRENT_BRANCH}" != "${TARGET_BASE}" ]]; then
    echo "Merging into wrong next, want ${TARGET_BASE}, have ${CURRENT_BRANCH}"
    exit 1
fi

git fetch "$REMOTE" pull/$PR_NUM/head

nr_commits=$(git log --pretty=oneline HEAD..FETCH_HEAD | wc -l)

closes="${NL}${NL}Closes ${PROJECT}#${PR_NUM}${NL}"

if [[ "$PR_TITLE" = *submodule* ]]; then
    ALLOW_SUBMODULE=1
fi

if [[ $nr_commits == 1 ]]; then
	commit=$(git log --pretty=oneline HEAD..FETCH_HEAD | awk '{print $1}')
	message="$(git log -1 "$commit" --format="format:%s%n%n%b")"
	if ! git cherry-pick $commit
	then
		echo "Cherry-pick failed. You are now in a subshell. Either resolve with git cherry-pick --continue or git cherry-pick --abort, then exit the subshell"
		head_before=$(git rev-parse HEAD)
		bash
		head_after=$(git rev-parse HEAD)
		if [[ "$head_before" = "$head_after" ]]; then
			exit 1
		fi
	fi
	git commit --amend -m "${message}${closes}"
else
	git merge --no-ff --log=1000 FETCH_HEAD -m "Merge '$PR_TITLE' from $USER_NAME" -m "${PR_DESCR}${closes}"
fi

mapfile -t files_changed < <(git diff --name-only HEAD~1 HEAD)
mapfile -t submodules < <(git show HEAD~1:.gitmodules | sed -n 's/.*path = //p')

submodules+=(.gitmodules)

# Check if any changed files are in submodule directories
has_submodule_changes=0
for submodule in "${submodules[@]}"; do
    for file in "${files_changed[@]}"; do
        if [[ "$file" == "$submodule" ]]; then
            has_submodule_changes=1
            echo "Found submodule change: $file"
        fi
    done
done

if (( has_submodule_changes && ! ALLOW_SUBMODULE )); then
    echo "ERROR: This pull request includes submodule changes but --allow-submodule flag was not provided"
    echo "NOTE:  The bad commit was left in the tree, do not push it."
    exit 1
fi

git commit --amend # for a manual double-check

# Check PR tests status
PR_HEAD_SHA=$(jq -r .head.sha <<< $PR_DATA)
PR_TESTS_STATUS=$(curl -s "https://api.github.com/repos/$PROJECT/commits/$PR_HEAD_SHA/status" | jq -r .state)
if [ "$PR_TESTS_STATUS" != "success" ]; then
  ORANGE='\033[0;33m'
  NC='\033[0m'
  echo -e "${ORANGE}\nWARNING:${NC} Some of the tests that ran for this PR were not completed successfully,\n" \
        "please make sure all tests are done successfully before merge this PR.\n"
fi
